MarelliMotori MEC-100 Manuel De L'utilisateur page 65

3.5.8. FCR (C8 Contact -
FCR enabling contact (normally open, switch logic): this input enables the FCR Mode for excitation current regulation (Field
Current Regulation, see Par. 3.4.4). FCR Mode can be automatically selected in case of loss of sensing and Shutdown Mode
enabled (see. Par. 5.7.8), and it does not depend on the status of FCR contact. When the FCR function is operating, the LED
corresponding to the Field Current Regulation FCR item in the system status window in System Monitoring becomes green.
WARNING: BE CAREFUL IN THE USE OF THE FCR MODE. The excitation current value in FCR mode must be
chosen considering the generator specifications and the operations to do: a too high excitation current value can
lead to over-excitation and/or overvoltage conditions dangerous for the generator and/or the plant (incautious use).
A initial low value is suggested, not higher than the excitation current in no load condition.
3.5.9. RESET (C8 Contact
Alarm reset contact (normally open, momentary pushbutton logic): this input allows to reset all active alarms as a result of the
intervention of one or more protections or limitations.
The alarm reset should usually be operated after the intervention on the system to remove the causes of the alarm
condition. If the system is still working and the alarm causes have not been removed, the RESET contact interrupts
the alarms for about a second, after which they are reactivated.
3.6. MEC-100 PROTECTIONS
The MEC-100 offers 7 protection functions which consist in transmitting externally a warning, of visual type, through MEC-100
Interface System, and/or of signal type, by associating this last to a relay.
3.6.1. Field Over-voltage Protection
When the measured field voltage increases above a value threshold which can be set, for a time interval whose length can be
established, the field over-voltage protection is activated. The activation of this protection is accompanied by a visual warning in
the MEC-100 Interface System (Field Overvoltage Protection item flashing, see Par. 5.8.3) and optionally can be associated to
one of the two programmable output relays.The activation voltage threshold can be set between 0 and 200Vdc with increases of
1Vdc and the operation time (measured by an internal timer) between 0 and 300s with increases of 0.1s. When the voltage falls
below the defined threshold, the protection timer is reset to zero. This function can be enabled/disabled.
3.6.2. Field Over-current Protection
When the measured field current increases above a value threshold which can be set, for a time interval whose length can be
established, the field over-current protection is activated. The activation of this protection is accompanied by a visual warning in
the MEC-100 Interface System (Field Overcurrent Protection item flashing, see Par. 5.8.3), and optionally can be associated to
one of the two programmable output relays. The activation current threshold can be set between 0 and 15Adc with increases of
0.1Adc and the operation time (measured by an internal timer) between 0 and 10s with increases of 0.1s. When the current falls
below the defined threshold, the protection timer is reset to zero. This function can be enabled/disabled.
3.6.3. Generator Over-voltage Protection
When the measured generator voltage increases above a value threshold which can be set, for a time interval whose length can
be established, the generator over-voltage protection is activated. The activation of this protection is accompanied by a visual
warning in the MEC-100 Interface System (Generator Overvoltage Protection item flashing, see Par. 5.8.3), and optionally can
be associated to one of the two programmable output relays. The activation voltage threshold can be set in the form of
percentage of the generator rated voltage, between 100 and 150% with increases of 1%, the operation time (measured by an
internal timer) can be determined between 0 and 300s with increases of 0.1s. When the voltage falls below the defined
threshold, the protection timer is reset to zero. This function can be enabled/disabled.
3.6.4. Generator Under-voltage Protection
When the measured generator voltage falls below a value threshold which can be set, for a time interval whose length can be
established, the generator under-voltage protection is activated.
The activation of this protection is accompanied by a visual warning in the MEC-100 Interface System (Generator Undervoltage
Protection item flashing, see Par. 5.8.3), and optionally can be associated to one of the two programmable output relays. The
activation voltage threshold can be set in the form of percentage of the generator rated voltage, between 0 and 100% with
increases of 1%, the operation time (measured by an internal timer) can be determined between 0 and 300s with increases of
0.1s. When the voltage increases above the defined threshold, the protection timer is reset to zero. This function can be
enabled/disabled.
963857137_M
only P.N. M71FA310A, M71FA320A)
–
only for P.N. M71FA300A)
MEC-100 – Marelli Motori
65